This invention relates to a crystalline polymorph form 2 of ethyl 4-(8-chloro-5,6,-dihydro-11H-benzo[5,6]cyclohepta[1,2-b]pyridin-11- ylidene)-1-piperidene carboxylate (hereinafter xe2x80x9cloratadinexe2x80x9d) represented by the formula

pharmaceutical compositions containing the polymorph form 2, and methods of using the polymorph form 2 to treat allergic reactions in mammals.
U.S. Pat. No. 4,282,233 discloses loratadine which possesses antihistaminic properties with substantially no sedative properties. This U.S. Pat. also discloses methods of making loratadine and using it to treat allergic reactions in mammals, but does not disclose or suggest the possible existence of a different polymorphic form.
To prepare pharmaceutical compositions containing loratadine for administration to mammals in accordance with exacting health registration requirements of the U.S. and international health registration authorities, e.g. the FDA""s Good Manufacturing Practices (xe2x80x9cGMPxe2x80x9d), there is a need to produce loratadine in as stable a crystalline form as possible, especially a form having constant physical properties.
We have discovered that loratadine can exist in the form of two distinct crystalline polymorphs, each having distinctly different physical properties.
Accordingly, this invention provides crystalline polymorph form 2 loratadine aracterized by the following x-ray powder diffraction pattern expressed in terms of xe2x80x9cdxe2x80x9d spacing and relative intensities(xe2x80x9cRIxe2x80x9d):
This invention also provides crystalline polymorph form 2 loratadine characterized by the following x-ray powder diffraction pattern expressed in terms of xe2x80x9cdxe2x80x9d spacings and relative intensities (xe2x80x9cRIxe2x80x9d)(s=strong, m=medium, w=weak, v=very and d=diffuse)
FIGS. 1A and 1B present a x-ray spectrum of crystalline polymorph form 2 loratadine
FIG. 2 presents the infrared spectrum of crystalline polymorph form 2 loratadine as a mull in mineral oil (Nujol) dispersion on a Mattson Galaxy 6021 FTIR spectrometer.